Electrode for electrically heated steam boilers and the like



N. HALLMAN Aug. 11, 1030.,

ELECTRODE FOR ELECTRICALLY HEATED STEAM BOILERS AND THE LIKE Filed Feb.2, 1955 Patented Aug. 11 1936 UNITED STATES PATENT OFFICE] ELECTRODE FORELECTRICALLY HEATED STEAM BOILERS AND THE LIKE Application February 2,1935, Serial No. 4,644 In Sweden February 10, 1934 2 Claims.

The present invention relates to electrically heated steam boilers andthe like constructed with a substantially circular cross-section andprovided with a plurality of current admission electrodes.

The main object of the invention is to provide for the greatest possibleuniformity in respect of the distribution of the current density withinthe boiler when in use, so as thereby to secure the greatest possibledistribution of the steam generation to the whole cross sectional areaof the boiler, and a facilitated escape of the steam mainly formed inthe proximity of the electrode rods.

In the art to which the invention relates it is known to construct theelectrodes in the shape of a group of vertically extending rods arrangedin a circle and supported by a common current admission member. It isalso known to provide a plurality of electrodes each of which istriangular in shape and having outer faces concentric with the shell andinner faces parallel to each other.

The object of my invention is to provide a novel arrangement ofelectrodes having certain characteristic features of both these knownconstructions but embodying also other specific features, novel per seand in combination, whereby there are insured a more nearly uniformdistribution of the current density and uniformity of the steamgeneration.

A preferable embodiment of the invention is illustrated in theaccompanying drawing in which:-

Fig. 1 shows a steam boiler constructed according to the invention andprovided with three current admission electrodes, seen in verticalsection, and

Fig. 2 is a cross section of the boiler at the line AB in Fig. 1.

Referring to the drawing, 1 is the boiler shell which is closed at theupper end by a cover 2 supporting the electrodes. Each of the electrodesconsists of a support plate 3 conductively connecting a plurality ofsubstantially vertical electrode rods inclining downwardly at a smallangle towards each other. In each electrode, these rods are positionedin an annular, or squirrel-cage, configuration, and the maincharacteristic of the invention is that the cross (horizontal) sectionof this configuration forms a circle sector, as will be seen from Fig.2.

If the boiler is provided with three current admission electrodes, asshown in the drawing, the angle of each of the sectors will be about(Cl. 2l940) 129, and since all of the sectors, besides having an equalradius, have also the same centre coinciding with the longitudinal axisof the circular boiler shell, the arcs of the same will be concentriowith the said shell.

While still adhering to the same principle of construction it isnaturally possible also to employ another number of electrode aggregatesthan that shown in the drawing for the sake of explanation.

In addition to the current admission electrodes described above, theboiler ought also to be provided with at least one current escapeelectrode, or zero voltage electrode, and this last mentioned electrodemay consist of the boiler shell a manner known per se. In order toarrive at the greatest possible uniformity in respect of thedistribution of the current density, and steam generation, this is notentirely sufiicient in all instances, however, when the currentadmission electrodes are constructed according to the invention. In suchinstances the preferred embodiment of the invention includes theprovision of radial metal plates within the boiler between the separatecurrent admission electrode aggregates 3, 4 such plates being,preferably, conductively connected with the boiler shell and serving toincrease the area of the current escape, or zero voltage, electrode.

The boiler shown in the drawing may naturally be fed both withsingle-phase and three-phase alternating current, as all of theelectrode aggregates 3, 4 may be connected with the same phase, or eachof them with a separate phase, respectively.

In case the boiler is intended to be fed with three-phase alternatingcurrent, the plates 5 may be omitted so that a direct currenttransmission between the phases may be obtained at the substantiallyradially extending portions of the sector-shaped electrode aggregates.

What I claim and desire to secure by Letters Patent is:

1. In an electrically heated steam generation means of the characterdescribed and which comprises a boiler shell of a substantially circularcross-sectional shape and having a substantially vertical axis and amultiplicity of current admission electrode rods extending downwardwithin the shell, the improvement which comprises such rods arranged ina uniformly distributed plurality of groups, the rods of each groupbeing electrically connected with each other and arranged in three rowsto form in horizontal cross-section the radii and are of a circlesector, the separate electrode of each group being positioned so to havea slight inclination toward each other in a downward direction so thatthe horizontal areas of sectors formed at difierent levelsprogressiveily decrease in a downward direction.

2. In an electrically heated steam generation means according to claim1, the additional feature of current escape electrodes comprisingvertically extending plates each positioned substantially radially ofthe shell and between and spaced from and approximately parallel to therows of rod electrodes which in cross-section form adjacent radii of twoadjacent sectors as specified.

NILS HALLMAN.

